EFFECT OF PROCESSING ON THE STRUCTURE, OXYGEN-CONTENT, AND SUPERCONDUCTIVITY OF LABA2CU3OY

We have examined the structure, oxygen content, and superconductivity of a LaBa2Cu3Oy superconductor heat treated at different temperatures and in different atmospheres. It was found that the expansion of the c -axis, which was caused by the removal of oxygen, might be the reason for the ordering of barium and lanthanum ions when the specimen is hea ted in a reducing atmosphere. The anomaly in the expansion of the c-ax is was also observed when oxygen was removed. Mechanisms of the orthor hombic-tetragonal transition and the occurrence of the anomaly in the c-axis have been proposed.